Testing apparatus for motor vehicles



July 12, 1932. w H E C TESTING APPARATUS FOR MOTOR VEHICLES OriginalFiled July 21, 1928 2 Sheets-Sheet l l I Invnr 569% July 12, 1932. w. H.WELCH TESTING APPARATUS FOR MOTOR VEHICLES Original Filed July 21, 19282 Sheets-Sheet 2 WE mzeg,

Patented July 12, 1932 UNITED STATES WALTER HENRY WELCH, F BRISTOL,ENGLAND TESTING AIElPARATUS FOR MOTOR VEHICLES Original applicationfiled July 21, 1928, Serial No. 294,535, and in Great Britain December30,

Divided and this application filed The present invention relates toimprovements in testing apparatus for motor vehicles and is a divisionof my application entitled Testing apparatus for motor vehicles, Ser.No. 294,535, filed July 21, 1928, which has resulted in Patent No.1,846,170, granted Feb.

This invention is for improvements in testing apparatus for motorvehicles whereby the eflicacy of the brakes can be measured; theapparatus may also be used for measuring the power available for drivingthe vehicle. The ability to test the brakes of a vehicle is ofimportance, particularly in regard to the setting 18 or adjustment ofthe brakes so that they are applied with equal force to both steeringwheels or to both driving wheels and in the correct ratio as betweendriving wheels and. steering wheels. It is a particular object of thepresent invention to provide an apparatus which can be constructed in asimple form for hand operation and can be used in places where externalpower for driving it, such as, for example, a generating set andconnections for actuating an electric motor, are not available. A.further object is to provide such a construction that the vehicle istested with its wheels in a natural or normal position bearing theweight of the vehicle. If a wheel of a vehicle is jacked up to render itavailable for testing, the distribution of the stresses and theclearances in the wheel, axle, springs and associated parts are quitedifferent from the normal running conditions so that a true readingcannot be obtained unless the wheel is supporting the vehicle in theordinary way.

A device, according to the present invention, for testing the powerapplied to the road wheels of a motor vehicle comprises a pair ofrollers whereon a road wheel can stand, one or both of which rollers canbe driven, means for measuring the torque applied thereto and means formeasuring the load on any wheel of the vehicle.

The desirable braking-effort for each road wheel is proportionate to theload on that wheel; hence, it follows that if the load on any wheel ofthe vehicle is known the proper braking force for that wheel can bedetermined. Another object of the present inven- 1927. July 11, 1931.Serial No. 550,234.

example, with reference to the accompanying U drawings in which Figure 1is a front elevation of one construction with its cover plate removed;

Figure 2 is a sectional elevation on the line 22 of Figure 1;

Figure 3 is a part-sectional plan on the line 33 of Figure 2;

Figure 4 is a similar view to Figure 1 of a modification 0f theapparatus; Figure 5v is a sectional elevation on the line 5-5 of Figure4c; 1

Figure 6 is a diagrammatic front elevation of a further modification.

Lke reference numerals indicate like parts in the various figures of thedrawings,

In the construction shown in Figures 1 to 3 inclusive, which is .similarto that described in the specification of my United States applicationNo. 294,535, a trough-shaped member 20 has a pair of rollers 21, 22mounted in it, one towards each end. These rollers may be cylindricalbut are preferably hollowed in longitudinal cross-section to accommodatethe tyre of the wheel 23 indicated in chainlines in Figures 1 and 2. Therollers may be roughened. ribbed or perforated to provide goodfrictional engagement with the tyre. On one side of the trough 20 thereis mounted a triangular upstanding casing formed in two parts 245. 25adapted to be secured together by bolts such. as are indicated at 26. I

Each of the roller shafts 27 28 extends into the said casing and carriesa chain sprocket 29, 30 respectively. At the apex of the triangularcasing there is loosely mounted on a shaft 31 another chain sprocket 32and a single chain 33 passes round the three sprockets. If the tworollers are operative to resist the braking force, the chain 33 connectsall the sprockets as above described, but if desired 'the chain 33 mayconnect only the sprocket 32 and one of the sprockets 29, 30, one of therollers 21, 22 being an idler. The chain sprocket 32 is coupled to agear wheel 34 also loose on the shaft 31 which engages a pinion 35 whichis loosely mounted on a secondary shaft 36 and is coupled to a gearwheel 37 also loose on the shaft 36. The gear wheel 37 meshes with apinion 38 fixed to the shaft 31, the whole constituting a reductiongear. The secondary shaft 36 is carried by radial arms 39, 40 and thearm 40 is extended downwardly towards the base of the casing. At itslower end, the arm 40 carries laterally projecting arms 41, 42, whichengage each one arm of a pair of bell-crank levers 43, 44, these leversbeing pivoted about vertical axes 45, 46 situated to the front of thearm 40. The other arms of the bell-crank levers 43, 44 are directedtowards one another and are connected by pins 47, 48 respectively tolugs 49 on a plate 50 adapted to bear against a flexible diaphragm 51forming one wall of a chamber 52 filled with oil or other suitableliquid.

The parts are so disposed that movement of the depending arm 40aforesaid in one direction or the other tends to rock one or other ofthe bell-cranks 43, 44 so that its other arm presses the plate 50 uponthe diaphragm 51 and is thereby restrained from further move ment. Itwill be understood that the other arms of the bell-cranks 43, 44 areslotted to permit the necessary movement relatively to the pins 47 48when the said bell-crank levers are rocked. The pressure exerted on thediaphragm is measured by means of a pressure gauge 53 in communicationwith the interior of the chamber 52.

It will be seen that when a vehicle is arranged with one of its drivingwheels on the rollers 21, 22 or each of its driving wheels on a separateapparatus, a drive can be imparted to the'driving wheels by means of ahandle 54 operating through the gearing and chain drive 33 to therollers 21, 22. When the brakes are applied additional efiort isrequired to turn the wheels, the reaction to this driving effort at thereducing gear being resisted by the oil in the closed chamber 52. Thereact-ion is measured by the pressure gauge 53 so that a reading of theabsolute braking effort is obtained.

The pressure gauge 53 may be calibrated to show the desirable brakingeffort for different weights of vehicles or this information may be readfrom a chart.

In the construction shown in Figures 4 and 5, a downwardly extending arm40 aforesaid carries laterally projecting arms 41, 42, in each of whichan adjusting screw 55, 56 is mounted. The said screws engage each onearm of a pair of bell-crank levers 43, 44 which are pivoted about theirhorizontal axes 45, 46 respectively. The other arms of these bell-cranklevers are directed towardsone another and bear on the upper end of a T-shaped presser 57 which is adapted to slide vertically between guides58.

The lower end of the presser 57 bears against a conical spiral spring 59formed of rectangular-section material mounted in a suitable casing 60.The underside of said spring is connected to a vertical bar 61 provided.with rack teeth which mesh with a pinion 62 fixed to a shaft to which isalso secured a gear wheel 63. This wheel meshes with a gear wheel 64fixed to an axle carrying the pointer of an indicating dial 65. Themechanismjust described will act in the same manner as that describedwith reference to Figures 1 to 3 and by adjusting the screws 55, 56, thesame reading can be obtained for either direction of rotation of themain shaft 31.

The apparatus shown in Figures 4 and 5 incorporates means for measuringthe load on a road wheel which means will now be described. It will beobvious that, if desired, this load-measuring means may be provided inthe construction shown in Figures 1 to 3.

The load-measuring means comprises a lever 66 which is disposed to oneside of the wheel-supporting roller 21 and is pivoted at one end to theside wall of the trough 20, as shown at 67 The other end of the pivotedlever 66 extends through an aperture 68 in the opposite side wall of thetrough 20 and the rear wall of the part 24 of the triangular casing.This end of the pivoted lever has a knife-edge which bears against asubstantially horizontal arm of a bell-crank lever 69, the other arm ofwhich is substantially vertical and carries a knife-edge 70 which bearsagainst the aforesaid downwardlyextending arm 40 of the torque-measuringmeans. Approximately at the mid-point of its length, the pivoted lever66 is fixed to a short vertical screw-threaded rod 71 by means of aforked head 72 on the latter and a bolt and nut 73. The screw-threadedrod 71 is engaged by a nut member 74 having a stem 75 adapted to projectthrough a hole 76 in the base of the trough 20.

In order to ascertain the load on the wheel, the wheel is supported onthe rollers 21, 22 and the nut member 74 is rotated for example, by atommy-bar, so that its stem 75 bears against the flooror ground.Continued rotation of the nut member will raisethe pivoted lever 66, thelatter will cause the bell-crank lever 69 to rock and the downwardlyextending arm 40 to swing so that the pressure 57 will press upon theconical spring 59. The pressure on said spring will be indicated on thedial 65 and when the pressure is equal to the load on the wheel furtherturning of the nut 74 will cause the apparatus to tilt as a whole aboutthe outer lower edge 77 (see Figure 4) of the triangular casing as afulcrum.

It will be appreciated that the various pivoted levers and arms may beso arranged and proportioned that the dial 65 will indicate the desiredproportion of the load on the 'wheel. This reading may be given in anydesired units and the knife edge 7 O on the bell-crank lever 69 and thedownwardly-extending arm 40 may be adjustably mounted so that they canbe set, for example, by means of bolts and nuts 78, 7 9 engaging slots80, 81 in the vertical arm of the bell crank-lever 69 and in the arm 40respectively.

Preferably, the mechanism is deslgned so that the maximum braking forcewhich can be used with a normal coefficient of friction on the roadgives the same reading on the dial as the weight of the vehicle. Thus,the provision and use of charts showing the desirable braking efiort fordifferent weights of vehicles is obviated since it is only necessary toascertain the load on the wheel and adjust the brakes to give the samereading.

Instead of turning the apparatus by hand, a small electric motor may beprovided for this purpose and, since such motors usually run at highspeed, it is desirable to take the drive from the motor through a wormgear to the reduction gearing described above. It will be appreciatedthat, owing to the large ratio of reduction, only a small motor isnecessary to turn the road wheels even when the brakes are stronglyapplied.

Instead of using the pressure gauge 53 to measure the torque, thedepending arm 40 of the reduction gear may be spring-controlled as showndiagrammatically in Figure 6. In this arrangement, two helical springs92 are provided whereof adjacent ends are connected to the depending arm40 as shown at 93 and the other ends are secured to the casing as shownat 94. The lower end of the arm 40 carries a stud 95 projecting througha slot 96 in the part 25 of the casing and which has at its outer end apointer 96 adapted to move over a scale 98. When the arm 40 moves fromits central position it compresses one and stretches the other of thesprings 92, variation in the length of the springs being a measure ofthe torque applied.

I claim In a device as specified, a roller support adapted to receive awheel of a motor vehicle thereon, gear means connected to the rollersupport for turning the same to rotate the wheel, an indicator,yieldable connecting means between the indicator and the gear means foroperation by the latter upon resistance to turning to actuate theindicator and measure the torque applied to the wheel, and weighingmeans between the roller support and said connection for operating thelatter by the weight on the support and showing such weight on theindicator.

In testimony whereof I affix my signature. I

WALTER HENRY WELOI-I.

